The present invention generally relates to conveyance technology, and more particularly to conveyance technology free from positional deviations.
As illustrated in FIG. 17, on a substrate 101 (such as, semiconductor wafer, etc.), a notch 102 indicating an orientation is formed at peripheral edge. In the case that the substrate 101 having the notch 102 is transferred by a transport robot, positional deviations will result.
In the case where a plurality of transport robots is used, errors are accumulated; thus, positional deviations of the substrate increase due to the following causes:    (1) in the case of significant number of delivery times of substrates;    (2) in the case of significant number of arms of transport robots, and variations occurring due to individual differences; and    (3) in the case where substrates happen to be directed toward different directions depending on positional relationship between delivery location and a plurality of transport robots.
In recent years, the number of processes that need to perform a high-accuracy centering of the substrate 101 and positioning of the notch 102 has been increased, and thus a problem of positional deviation of the substrate 101 cannot be neglected.
Also, an increase in effective area on the substrate is desired. For example, as an effective region where chips can be taken on the substrate 101, in a substrate having 200 mm in diameter, inner radius region of 5 mm or inside from the edge is regarded as an effective region. Although it was satisfactory if only the quality of film is ensured within the effective region, for a substrate having 300 mm in diameter, however, it is required that an inner radius region of 3 mm or less from the edge should be ensured as an effective region; accordingly, a permissible value of conveyance deviations becomes smaller.
In addition to a condition in which the inner radius region of 3 mm or less from the edge should be an effective region, in order that a substrate stage may not be exposed to the bottom surface of the notch 102, since the notch 102 has been notched by 1.5 mm, another condition in which conveyance precision of the substrate being within 1.5 mm must also be met. In complicated processes where superimposing of conveyance precisions frequently occurs, or in processes where positional deviations of the substrate 101 cannot be permitted, the need to perform a precise positioning of orientations of the notch 102 has also arisen.
A reference numeral 105 in FIG. 18 denotes a vacuum processing equipment of which a plurality of processing chambers 112 to 116, and 122 to 126 is connected to each other. In two sets of transport chambers 110 and 120, transport robots 118 and 128 are arranged, respectively, and the conveyance chambers 110 and 120 are connected via a delivery chamber 130.
A stand 131 is arranged within the delivery chamber 130. The objects to be transported are taken out from the processing chambers 112 to 116 by a transport robot 118 provided in the transport chamber 110 at one side and the objects are arranged on the stand 131, then the objects to be transported are carried in the processing chambers 122 to 126 connected to a transport chamber 120 at the other side by the transport robot 128 provided in the transport chamber 120 at the other side.
In this figure, reference numerals 141 to 143 denote objects to be transported held on the stand 131, the objects to be transported being substrates with notches formed thereon.
The transport robots 118 and 128 have hands 135a, 135b, 145a and 145b at the ends of telescopic arms 137 and 147, respectively. When the objects to be transported 141 to 143 are placed on the hands 135a, 135b, 145a and 145b, respectively, and arranged at different positions on the stand 131, the transport robots 118 and 128 extend the arms 137 and 147 by rotating the arms 137 and 147 around rotating shafts 119 and 129 as a center.
Thus, orientations of the hands 135a, 135b, 145a and 145b will not become parallel to each other when the objects to be transported 141 to 143 are arranged at different positions on the stand 131. For this reason, even if the notches 146 to 148 of the respective objects to be transported 141 to 143 arranged on the hands 135a, 135b, 145a and 145b of the transport robots 118 and 128 are faced toward a given direction, the notches 146 to 148 of the objects to be transported 141 to 143 arranged on the stand 131 will face different directions.
The orientation deviations of the notches 146 to 148 become more widened when the objects to be transported 141 to 143 are transferred from one to another of two sets of the transport robots 118 and 128.
In order to solve the above-mentioned drawbacks, there is an example in which a correcting and moving device for rotating the objects to be transported 141 to 143 is provided to correct the orientations of the notches 146 to 148; and the transport robot and the correcting and moving device are alternately operated to carry out positional corrections. There is a problem, however, in that the transport robot cannot transfer the substrates during the correction of substrate positions so that throughput is reduced.
Also, deviations of the central positions of the objects to be transported 141 to 143 in the delivery chamber 130 may present a problem. In the conventional art, a correction is made by means of a device as shown in FIGS. 19(a) and (b).
FIG. 19(a) illustrates a state in which a substrate 151 transferred from the transport robot and held on a pin 155 at a location having distance regulating members 154a and 154b positioned right and left. When the pin 155 is caused to fall, the substrate 151 comes into contact with the seating faces of the regulating members 154a and 154b, and the regulating members 154a and 154b rotate around center shafts 156a and 156b, thereby the side walls of the regulating members 154a and 154b become erect.
At this time, even if the substrate 151 is deviated to either right-hand or left-hand side, the substrate 151 is pressed against the side walls on their way to an erection, and then the substrate is moved to a position sandwiched between the side walls so that the deviation will be corrected.
In the case in which a mechanical centering is performed in this manner, the regulating members 154a and 154b come into contact with the substrate 151; and accordingly, there is a problem in that dust is produced. In addition, a positioning mechanism is difficult to adjust. This conventional art are disclosed in JPA 10-270533 and JPA 8-46013.